Signaling system control



Jan. 24, 1933. L. A. GEBHARD SIGNALING SYSTEM CONTROL Filed June 4, 1929 A TTORNEY Patented Jan. 24, 1933 Aral" orrie LOUIS A. G-EBHARD, 0F WASHING-TON, DISTRICT 6F COLUMBIA, ASSIGNOR TO WIRED RADIO, ENG, OF NEW YCRK, N. Y., A CORPORATION 01 DELAWARE SIGNALING SYSTEM CGNTROL- Application filed. June 4, 19:39.

My invention relates broadly to signaling systems and more particularly to the control of signaling systems.

One of the objects of my invention is to provide an arrangement whereby the operation of signaling systems may be readily and efficiently controlled.

Another object of my invention is to provide an arrangement whereby the output of signaling systems may be readily and efficiently controlled.

Still another object of my invention is to provide an arrangement whereby the output of a signaling system may be modulated for the transmission of intelligence.

A further object of my invention is to provide an arrangement whereby the output of a signaling system may be readily modulated by varying the potential of one of a plurality of grid electrodes of an electron discharge device which is adapted to increase the magnitude of the signaling energy.

A still further object of my invention is to provide an arrangement whereby the output of a shield grid electron discharge device is modulated for the transmission of intelligence by varying the magnitude of the potential impressed upon the shield grid electrode. Other objects and features of my invention will be apparent to those skilled in the art to which this invention relates from the following specification and the accompanying draw- I liccording to my invention the output of signaling systems employing one or more shield grid electron discharge devices is controlled readily and efficiently by controlling the magnitude and polarity of the potential impressed upon. the shield grid electrode of one of the electron discharge devices which functions to increase the magnitude of the signaling energy. Under normal operating conditions the shield'grid electrode is maintained at a positive potential with respect to the cathode. In accordance with my invention I provide an arrangement in which a high impedance unit is connected into the shield grid electrode circuit of an electron discharge device amplifier and the positive terminal of the source of potential which is Serial No. 368,321.

connected with the shield grid electrode, and in which another source of potential is connected with a relay system so that a negative potential is impressed upon the shield grid electrode upon the deenergization of the relay system. WVhen the relay system is energized the normal operating positive potential is applied upon the shield grid electrode of the electron discharge amplifying device and signaling energy of increased magnitude is rendered available in the output circuit of the device.

The operation and details of my invention will be more thoroughly understood from the following specification and the drawing in which the sole figure illustrates the preferred embodiment of my invention.

Reference number 1 designates a constant frequency oscillation source including an electron discharge device 2, a frequency determining and stabilizing element 3, which may be of the piezo electric crystal or the magnetostriction type, and an output circuit 4. A shield grid electron discharge device 5, having a cathode 5a, a grid electrode 56 and an anode 501, is connected to the circuits of the oscillation generator 1 for increasing the a1nplitude of the oscillations developed by the oscillation generator. A choke coil 6 is connected to the grid electrode 5b of device 5 to prevent high frequency oscillations of large amplitude from being impressed upon the direct current source 17 which is employed as a source of grid biasing potential for the device 5. A condenser 8 is connected between the low voltage end of the choke coil 6 and the cathode circuit of the devices 1 and 5 to provide a. low impedance path for high frequency oscillations transmitted through the choke coil 6. The positive terminal of the source 17 is connected to the cathode circuit of the devices 1 and 5. A coupling condenser 7 is provided for the input circuit of device 5 for coupling the output circuit 4 to the grid prising the generators 24 and 25, is connected between the cathode and anode circuits of these devices.

This source of anode current may consist 5 of a battery of any of the well known types or of a rectified alternating currentsource in place of theIgenerators24 and 25, illustrated in the drawing. Likewise the source 17may also consist of any of the well known sources of direct current." Where-at battery is employed as a source of anode current-for the devices 2 and 5 a portion of l maybe used to furnish. the rid bias )otential for the device 5 in place of the source 1(.

24 to, provide means for. reducing :the; potenl appl edtothe n daof thedevicea A high resistance nnit .QLis connected. between th'efshield grid electrode 5c and :the positive terminal;of the. source 24. This resistance,

maybe of the orderof-IOQOOO ohms. A relay 20 is connected between, the shield; grid electrodefic and the negative terminal of the source 17. lV-hen the ley.:23 is released. the

-e. ui f. e r ay 0 an the source .22 of lay nergi ng. urrent s in rrupted and the circuit between the shield grid electrode,

50 and vthe negative terminal of; the source 17 is closed wherebythe negative potent al of thesour ce 17 is impressed upon the shield gr d electrode 5c and the electron discharge device 5'ceases to functiozras an;an ipl fier.;

When the key 23 is depressed therelay 20 an amplifier. The output of the electron discharge device amplifier .5 is thus controlled by the key 1.23 through theactionofthe rela shield. grid;electrode andthe cathode 5a,

45 :Another condenser 11 isconnected between; the inductancei) and the cathode 5a. These condensers are employed to provide low impedance paths forhigh frequency oscillations, A condenser 19 and a variablere sister 18 may be connected in series across the contacts of relay 20 to act as an absorption circuit and rend-er sparking the con-, tacts of the relay neglig ble... The antenna,

circuit comprising the antenna 15, the series tuning condenser 14, the variable inductance 13 and theground connection 16 is coupled to the outputcircuitof the device 5fthro ugh the variable capacity .12.

Practically no'radio frequency. voltage 0 ists. between shielding grid. 50 and-cathode 5a..be.cause by-pass condenser 10 connected between "the shielding .grid and cathode will 1 V Toy-pass, practically all of any such radio:

frequency [voltage and the radio frequency ;..potentiahof the shielding; will be that po tentiometer 26 is connected across the source A condenser 10 is connected between; the

of the cathode. be blocked by a direct current potential applied to shielding grid 50 of very considerably less value than would be required if the keying negative biasing voltage were applied to the-control grid 5?) on-which a radio frequency. voltage with reference to the cathode necessarily exists. By the use of my system, the blocking keying potential. applied to the shield grid may be as small; orsmaller, than the normal control grid negativebias. The figure showsthe use of the same source 1.7 for the normal control grid bias, and also for the negatie keying. blocking potential impressed on the shielding grid. In the keying {systems heretofore employed in which negativeblockingpotential isimpressed upon the control grid of a three-electrodestube, which grid-mustbe maintained at a considerable. radio frequency potentialto. maintain oscillations, the negative potential required to block the grid is far higher thanany nor: mal grid biasing; potential, andthis fact greatly'increases. theipractical difliculties of keying in operation.v Mymethod of-=keying the shielding grid is thereforea substantial improvement over methods heretofore em.- ployed..

Whereit isldesired-a greater number. of electron discharge devices than is illustrated.

inthe drawingmay beemployed to increase the amplitude ofthe,high frequency oscil lationsv The outputs of other arrangements in which a seriesof frequency multiplying electron discharge devices are employed may also be controlled .in accordance with this in vention. Various other modifications ofthis invention may be madeW-ithout departing from the scopeandspirit.{thereof and it is thereforennderstood thatnI'do not desire to. limitqny invention to the. exact detailsas set forthin the foregoing specification ex- For this reason tube 5 can cept in so far as thesedetailsmay be. defined by. the appended claims.

lVhat I- claim .as; newand desire to secure by. Let ers Patent of the ,U-nited States is as follows; I

1. In a keying system for a radio telegraph 5 transmitter, an .electron tube having cathode-anode control grid andshielding grid,,said shielding grid being adjacent said anode, a source of. anode potential :connected to said anode, oscillating v circuits connecting the electrodes of said-tube, asource ofdirect current negative bl-aSIIIgPOt'B-D-Ual connected apply to saidshielding grid a-negative po-.

nected throughl said current limiting resist- .120 to .saidshielding grid of;,value sufiicientto ance between. said shielding grid and 'said' cathode, and means inserted in'the circuit connect ng said source. ofnnegativebiasing Lesa potential to said shielding grid for interrupting the application of said negative biasing potential to said shielding grid in accordance with a communication code, whereby the transmission of energy from the on 1 put circuit of said tube is controlled in accordance with said communication code.

2. In a keying system for a radio telegraph transmitter, an electron tube having cathode, anode,'control grid and shielding grid, said shielding grid being adjacent said anode, a source of anode potential connected to said anode, oscillating circuits connecting the electrodes of said tube, a source of direct current negative biasing potential connected to said shielding grid of value suflicient to apply to said shielding grid a negative potential which will prevent the delivery of oscillations in the output circuit of said tube,

a high current limiting resistance, a source of positive biasing potential for normal operation connected through said current limiting resistance between said shielding grid and said cathode, a radio frequency by-pass condenser connected between said shielding grid and said cathode for avoiding the maintenance of radio frequency potentials on said shielding grid, and means inserted in the circuit connecting said source of biasing potential to said shielding grid for interrupting the application of said negative biasing potential to said shielding grid in accordance with a communication code, whereby the transmission of energy from the output circuit of said tube is controlled in accordance with said communication code, and the voltage interrupted during keying has a minimum value.

3. In a keying system for a radio telegraph transmitter, an electron tube having cathode, anode, control grid and shielding grid, said shielding grid being adjacent said anode, a source of anode potential connected to said anode, a source of negative control grid biasing potential connected to said control grid of value suitable for normal operation of said tube, oscillating circuits connecting the electrodes of said tube, a source of direct current negative shielding grid biasing potential connected to said shielding grid 01 value su'lficient to apply to said shielding grid a negative potential which will prevent the delivery of oscillations in the output circuit of said tube, a radio frequency by-pass condenser connected between said shielding grid and said cathode for avoiding the maintenance of radio frequency potentials on said shielding grid, the voltage of said source of shielding grid biasing potential not exceeding the voltage of said source of control grid biasing potential, and means inserted in the circuit connecting said source of shielding grid biasing potential. to said shielding grid for interrupting the application of said negative biasing potential to said shielding grid in accordance with a communication code, whereby the transmission of energy from the output circuit of said tube is controlled in accordance with said communication code.

l. In a keying system for a radio telegraph transmitter, a master oscillator electron tube, input and output circuits therefor, a power amplifier electron tube having cathode, anode, control grid and shielding grid electrodes, the output circuit of said master oscillator tube being connected to the control grid of said power amplifier tube, a source or" anode potential connected to the anode of said power amplifier tube, oscillating circuits connecting the electrodes of said power amplifier tube, a source of direct current negative biasing potential connected to said shielding grid of value suliicient to apply to said shielding grid a ne ative potential which will prevent the delivery of oscillations in the output circuit of said power amplifier tube, a high current limiting resistance, a source of positive operating biasing potential connected through said current limiting resistance between said shielding grid and said cathode, and means insorted in the circuit connecting said source oi" biasing potential to said shielding grid for interrupting the application of said negative biasing potential to said shielding grid in accordance with a communication code, whereby the transmissiin of energy from the output circuit of said power amplifier tube is controlled in accordance with said communication code.

5. In a keying system for a radio telegraph transmitter, a master oscillator electron tube, input and output circuits therefor, a power amplifier electron tube having cathode, anode, control grid and shielding grid elec trodes, the output circuit of said master oscillator tube being connected to the control grid of said power amplifier tube, a source of anode potential connected to the anode of said power amplifier tube, oscillating circuits connecting the electrodes of said power amplifier tube, a source of direct current negative biasing potential connected to said shielding grid of value suificient to apply to said shielding grid a negative potential which will prevent the delivery of said oscillations in the output circuit of said power amplifier tube, a high current limiting resistance, a source of positive operating biasing potential connected through said current limiting resistance between said shielding grid and said cathode, a radio frequency by pass condenser connectedbetween said shielding grid and said cathode for avoiding the maintenance oi radio trequecy potentials on said shielding grid of said power amplifier tube, and means inserted in the circuit connecting said source of biasing potential to said shielding grid for interrupting the application of said negative biasing potential to said shieldand'iduring, spacing-intervals between signals applying --to-sa1d shielding gl'lCliL negative ingg-rid in accordance with ,aqcor'nmunicationi code,- whereby the tIElIlSIIllSSlOIl: of energy' fronrthe output: circuit of'said power amplifier tubeis controlled inaocordance with said'; 9 communication code, a and the voltage lnterrupted during keying has a minimum 1 value.

6.,In: a radio telegraph transmitter emr' playing 1 a four-electrode shielding 1 grid tube, the methodof keying-Which consists innor- 1 mallyapplying to said shieldinggrid when:

a signalis transmitted, a biasing potential positive Withreference to said cathode/and ofvalue suitable for= maintaining oscillations biasinfgpot-ential with reference to the cat-h: ode; 0 :value *exceedlng said normal positive biasing; potential and sufiicient to cause the,

blocking of the operationof said four-electrode :tube. V

LOUIS GEBHARDF 

